1. Field of the Invention
The present invention relates to a remote control apparatus for a boat and, in particular, to a remote control apparatus that minimizes variations among propulsion units of a boat.
2. Description of the Related Art
A remote control apparatus allows an operator to control the operation of the propulsion units of a boat. A throttle opening of a propulsion unit is typically controlled by setting a corresponding control lever at a particular position. The throttle opening of each propulsion unit in a multi-propulsion unit boat may be different because detection sensors for detecting the positions of associated control levers may have variations in performance. Consequently, the rotational speeds of the output shafts of the respective propulsion units will often be different. As a result, an operator of a boat having a plurality of propulsion units may not be able to operate the boat in a manner in which the operator intends.
To reduce or eliminate variations in the rotational speeds of the output shafts of the propulsion units due to variations in control lever position readings, conventional remote control apparatuses are usually adapted for calibration.
Calibration involves setting correction values optimum for the individual circuits of the respective propulsion units based on the actual positions of the associated control levers and the positions detected by corresponding sensors. The correction values that are optimum for the individual circuits of the respective propulsion units are commonly written into storage devices of associated electronic control units, which typically are provided outside of the remote control apparatus. The electronic control units control the propulsion units based on the correction values so that, ideally, the same desired operation of respective propulsion units will provide the same rotational speed of the output shafts of the respective propulsion units.
There are some problems, however, that are presented by the calibration process. Conventional calibration systems typically involve many complicated steps and can be difficult to execute properly. Meanwhile, calibration is often performed by end-user customers who purchased boats after the boats have been delivered by a manufacturer. The calibration process can be burdensome for such end-user customers who may lack the sophistication necessary to properly calibrate the propulsion units.
Monitor-display calibration systems can be problematic as well. Some remote control apparatuses are designed to make calibration easier so that end-user customers can perform calibration by following an operation guide screen displayed on a monitor. In such apparatuses, an operator can switch from a normal operational mode to an inspection mode that allows the operator to calibrate the propulsion units of a boat. In these systems, however, the operator might inadvertently switch to the inspection mode while operating the boat, which could have an undesirable effect on the operation of the boat.